Coated article and method for manufacturing same

ABSTRACT

A coated article includes a substrate including a porous surface and an anodic oxidation film. The porous surface defines a plurality of nanopores. The anodic oxidation film is formed on the substrate covering the porous surface by anodic oxidation process. The anodic oxidation film has a plurality of bonding protrusions, and each bonding protrusion is retained in one of the nanopores to improve a binding force between the substrate and the anodic oxidation film.

BACKGROUND

1. Technical Field

The disclosure generally relates to coated articles and method formanufacturing the coated articles.

2. Description of Related Art

For improving corrosion resistance of metal, such as aluminum oraluminum alloy, physical vapor deposition (PVD) can be used to deposit acoating on a surface of the metal. However, coatings deposited by PVDtypically contain micropores that can allow penetration of contaminants,such as air and moisture, which can corrode the metal.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the exemplary coated article andmethod for manufacturing the coated article. Moreover, in the drawingslike reference numerals designate corresponding parts throughout theseveral views. Wherever possible, the same reference numbers are usedthroughout the drawings to refer to the same or like elements of anembodiment.

FIG. 1 illustrates a cross-sectional view of a substrate of anembodiment of a coated article, in which a plurality of nanopores aredefined in the substrate.

FIG. 2 illustrates a cross-sectional view of an embodiment of a coatedarticle.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a coated article 100 includes a substrate10, an anodic oxidation film 20 deposited on the substrate 10 and acolor layer 30 deposited on the anodic oxidation film 20. The coatedarticle 100 may be a housing of an electronic device.

The substrate 10 may be made of aluminum or aluminum alloy. Thesubstrate 10 includes a porous surface 12 that defines a plurality ofnanopores 122 made by electrochemical etching. Each nanopore 122 has apore opening size between 8 nanometers (nm) and 20 nm in circumference.In this exemplary embodiment, each nanopore 122 has a pore opening sizebetween 10 nm and 15 nm.

The anodic oxidation film 20 is formed on the substrate 10 covering theporous surface 12 by anodic oxidation process. The anodic oxidation film20 has a plurality of bonding protrusions 22, and each bondingprotrusion 22 enters into one of the nanopores 122 so the anodicoxidation film 20 is firmly attached to the substrate 10 by thecombination of the bonding protrusions 22 and the nanopores 122. Theanodic oxidation film 20 has a thickness between about 5 micrometers andabout 20 micrometers.

The color layer 30 is formed on the anodic oxidation film 20 opposite tothe substrate 10 by vacuum deposition. The color layer 30 has athickness between about 0.5 micrometers and about 2 micrometers. Thecolor layer 30 may be a titanium nitride (TiN) layer, a titaniumnitric-oxide (TiNO) layer, a titanium carbon-nitride (TiCN) layer, achromium nitride (CrN) layer or a chromium carbon-nitride (CrCN) layer.

A method for manufacturing the coated article 100 may include at leastthe following steps.

Providing a substrate 10. The substrate 10 may be made of aluminum oraluminum alloy.

Pre-treating the substrate 10 by washing the substrate with a solution(e.g., deionized water or acetone) in an ultrasonic cleaner, to removeimpurities, such as grease or dirt. The substrate 10 is dried. Thesubstrate 10 is then treated by alkali treatment in the following way:dipping the substrate 10 in a solution including about 30-50 g/L of NaOHand about 1-2 g/L of sodium gluconate at a temperature of about 40Celsius degree (° C.)-60° C. for a time of about 1 minute-5 minutes.

The substrate 10 is electrochemically etched to form a porous surface 12with a plurality of nanopores 122. During electrochemical etching, thesubstrate 10 acts as an anode, a platinum plate acts as cathode, usingabout 20 g/L-30 g/L of hydrochloric acid or about 250 g/L-350 g/L ofsulphuric acid as electrolyte. A constant power having a current densitybetween about 6 A/d m² and about 10 A/d m² is applied between the anodeand the cathode for about 5 minutes to about 10 minutes to form theporous surface 12.

The substrate 10 is treated by anodic oxidation process, to form ananodic oxidation film 20 on the porous surface 12. Sulphuric acid havingabout 180 g/L-220 g/L is used as electrolyte. The electrolyte has atemperature between about 19° C. and 21° C. A constant power having acurrent density between about 1 A/m² and about 1.5 A/m² is applied tothe electrolyte for about 20 minutes to about 40 minutes to form theanodic oxidation film 20. During depositing the anodic oxidation film20, portions of the anodic oxidation film 20 enter into the nanopores122 to form a plurality of bonding protrusions 22. Additionally, eachbonding protrusion 22 is retained in one of the nanopores 122 to improvea binding force between the substrate 10 and the anodic oxidation film20.

The substrate 10 is dipped in an about 5 g/L-10 g/L of nickel acetatesolution at a temperature between 90° C. and 100° C. for a time of 10minutes to 15 minutes, to seal the anodic oxidation film 20. Therefore,corrosion resistance of the anodic oxidation film 20 is improved.

A color layer 30 is deposited on the anodic oxidation film 20 by vacuumdeposition, such as vacuum sputtering or vacuum evaporation.

In above exemplary, the substrate 10 defines a plurality of thenanopores 122, the anodic oxidation film 20 includes a plurality of thebonding protrusions 22. Each bonding protrusion 22 is retained in one ofthe nanopores 122 so a binding force between the substrate 10 and theanodic oxidation film 20 can be improved. Additionally, the anodicoxidation film 20 can prevent the coated article from electrochemicallyetching.

It is to be understood, however, that even through numerouscharacteristics and advantages of the exemplary disclosure have been setforth in the foregoing description, together with details of the systemand function of the disclosure, the disclosure is illustrative only, andchanges may be made in detail, especially in matters of shape, size, andarrangement of parts within the principles of the disclosure to the fullextent indicated by the broad general meaning of the terms in which theappended claims are expressed.

1. A coated article, comprising: a substrate including a porous surface,the porous surface defining a plurality of nanopores; and an anodicoxidation film formed on the substrate covering the porous surface byanodic oxidation process; wherein the anodic oxidation film has aplurality of bonding protrusions, and each bonding protrusion isretained in a nanopore to improve a binding force between the substrateand the anodic oxidation film.
 2. The coated article as claimed in claim1, wherein the substrate is made of aluminum or aluminum alloy.
 3. Thecoated article as claimed in claim 1, wherein the nanopores are formedby electrochemical etching.
 4. The coated article as claimed in claim 1,wherein each nanopore has a pore opening size between 8 nm and 20 nm incircumference.
 5. The coated article as claimed in claim 1, wherein eachnanopore has a pore opening size between 10 nm and 15 nm incircumference.
 6. The coated article as claimed in claim 1, wherein theanodic oxidation film has a thickness between about 5 micrometers andabout 20 micrometers.
 7. The coated article as claimed in claim 1,further comprising a color layer formed on the anodic oxidation filmopposite to the substrate.
 8. The coated article as claimed in claim 7,wherein the color layer has a thickness between about 0.5 micrometersand about 2 micrometers.
 9. The coated article as claimed in claim 7,wherein the color layer is one selecting from a group consisting of atitanium nitride layer, a titanium nitric-oxide layer, a titaniumcarbon-nitride layer, a chromium nitride layer and a chromiumcarbon-nitride layer.
 10. A method for manufacturing a coated article,the method comprising: providing a substrate, the substrate including aporous surface, the porous surface defining a plurality of nanopores;forming an anodic oxidation film on the substrate covering the poroussurface by anodic oxidation process; during forming the anodic oxidationfilm, portions of the anodic oxidation film enter into the nanopores toform a plurality of bonding protrusions, and each bonding protrusion isretained in one of the nanopores to improve a binding force between thesubstrate and the anodic oxidation film.
 11. The method of claim 10,wherein the substrate is made of aluminum or aluminum alloy.
 12. Themethod of claim 10, wherein before the anodic oxidation film isdeposited on the substrate, the substrate is treated by alkalitreatment.
 13. The method of claim 12, wherein during the substrate istreated by alkali treatment, the substrate is dipped in a solutionincluding 30-50 g/L of NaOH and 1-2 g/L of sodium gluconate at atemperature of 40-60° C. for a time of 1-5 minutes.
 14. The method ofclaim 10, wherein the nanopores are defined by electrochemical etching.15. The method of claim 14, wherein during electrochemical etching, thesubstrate acts as an anode, a platinum plate acts as cathode, using20-30 g/L of hydrochloric acid or 250-350 g/L of sulphuric acid aselectrolyte, a constant power applied between the anode and the cathodehave a current density between about 6 A/d m² and about 10 A/d m² forabout 5 minutes to about 10 minutes to define the nanopores.
 16. Themethod of claim 10, wherein during anodic oxidation, using 180-220 g/Lof sulphuric acid as electrolyte, the electrolyte has a temperaturebetween 19° C. and 21° C., a constant power applied to the electrolytehas a current density between about 1 A/m² and about 1.5 A/m² for about20 minutes to about 40 minutes to form the anodic oxidation film. 17.The method of claim 10, wherein after depositing the anodic oxidationfilm, the substrate is dipped in a 5-10 g/L of nickel acetate solutionat a temperature between 90° C. and 100° C. for a time of 10 minutes to15 minutes, to improve corrosion resistance of the anodic oxidationfilm.
 18. The method of claim 10, further comprising a step ofdepositing a color layer on the anodic oxidation film by vacuumdeposition.